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Re: Soil Compaction in Pasture
- To: forage-mg@oes.orst.edu
- Subject: Re: Soil Compaction in Pasture
- From: "E. Ann Clark, Associate Professor" <ACLARK@crop.uoguelph.ca>
- Date: Thu, 14 Sep 1995 11:00:52 EDT
- Organization: Crop Science, The Univ. of Guelph
- Priority: normal
Phil: I would have made the same assumption, but for two points.
First, the Aerway rotovator device (rotating cylinder with knives to
slit open the soil) originated, I believe, in the UK or nearby, where
stock are out and grazing on heavier, wetter soils, for longer times,
than we might do. Under those conditions, the Aerway or like devices
seem to be necessary to overcome the compactive effect of livestock,
or wheel traffic, or whatever.
Secondly, we did a multi-year trial at a heavy, wettish (but tile
drained), silty, clay loam, 10 ac site here at Guelph. The study
compared a) clipping vs. grazing by b) cattle or c) sheep. Species
persistence in mixture differed sharply between clipped and grazed
conditions, so in trying to interpret why, one of the measurements
was of soil fertility after 5 years of these treatments. My
technician broke several sampling units in sampling the cattle-grazed
treatments, but had no difficulty getting samples in the clipped
treatments. Bred heifers and dry cows grazed these treatments most
of the season, but were withdrawn when conditions were just too wet
and pugging was a problem. So, the kind of compaction we observed
might be considered typical - not from mismanagement - for heavy, wet
soils.
Might add, however, that the sampling exercise was done at the
end of the season. Winter freeze/thaw activity might well have
loosened this up considerably by the following spring, so I wouldn't
want to overinterpret the "busted sampler" example. Also, the degree
of compaction - whatever and however long it persists each season -
is not enough to prevent strong sward growth. We are now in the 6th
grazing year on those swards (different trial now), and growth has
been outstanding this season, in spite of two, 3-week droughts, one
in June and the other in August. Ann
ACLARK@crop.uoguelph.ca
Dr. E. Ann Clark
Associate Professor
Crop Science
University of Guelph
Guelph, ON N1G 2W1
Phone: 519-824-4120 Ext. 2508
FAX: 519 763-8933